Conventionally, a technique is well known such that a backup data of a vehicular device such as a vehicular navigation device and an EMV (electro multi vision system), which is supplied energy from a power source of a vehicle, is stored in a non-volatile memory. The non-volatile memory has the limitation of the number of storing times, and it is necessary to perform a process such as a charge correction process in case of read out. Thus, when the non-volatile memory is used in the vehicular device, it is necessary to limit the number of storing times and the number of read out times for the non-volatile memory in view of long term stability of the non-volatile memory. Accordingly, with respect to a large amount of data and frequently updated data, a suitable action is taken for the data to store in the non-volatile memory when an accessory switch turns off.
When a large amount of data or frequently updated data is stored in the non-volatile memory, it takes too much time to store the data. Even if the accessory power source turns on again while storing the data, a conventional technique cannot suspend storing the data into the non-volatile memory, and reboot an application software in the vehicular device. Thus, a difficulty arises that the reboot process time is increased.
However, for example, the Patent Literature 1 discloses a technique for continuing a power supply to the vehicular device for a predetermined period and maintaining an activation state of the vehicular device after a vehicular switch turns off. In the Patent Literature 1, using this technique, just after the vehicular switch turns on, the vehicular device is in an available state.
However, even when the technique disclosed in the Patent Literature 1 is applied, it is necessary to suspend a reboot of an application software in the vehicular device until a storing process is completed in a case where an user turns on the vehicular switch at a timing during the backup data is being stored in the non-volatile memory.